BACKGROUND AND PURPOSE:There is a high incidence of intracranial aneurysms of the AcomA suggesting the possibility of an anatomic risk factor. There also exists an association of terminationtype aneurysms with anatomic variations of 1 anterior cerebral artery trunk (A1) as the exclusive or dominant supply to both pericallosal arteries (A2). This yields the hypotheses of aneurysm formation from straight jets of A1 blood.

BACKGROUND AND PURPOSE:Anterior communicating artery aneurysms account for one-fourth of all intracranial aneurysms and frequently occur in the context of A1 vessel asymmetry. The purpose of this study was to correlate circle of Willis anatomic variation association to angiographic and clinical outcomes of anterior communicating aneurysm coiling.

Background— Abnormal intercellular communication caused by connexin dysfunction may contribute to atrial fibrillation (AF). The present study assessed the effect of the gap junction conduction–enhancing antiarrhythmic peptide GAP-134 on AF inducibility and maintenance in a dog model of atrial cardiomyopathy. Methods and Results— Twenty-four dogs subject to simultaneous atrioventricular pacing (220 bpm for 14 days) were randomly assigned to placebo treatment (PACED-CTRL; 12 dogs) or oral GAP-134 (2.9 mg/kg BID; PACED-GAP-134; 12 dogs) starting on day 0. UNPACED-CTRL (4 dogs) and UNPACED-GAP-134 (4 dogs) served as additional control groups. Change in left atrial (LA) systolic area from baseline to 14 days was calculated using transoesophageal echocardiography. At 14 days, animals underwent an open-chest electrophysiological study. PACED-CTRL dogs (versus UNPACED-CTRL) had a shorter estimated LA wavelength (8.0�1.4 versus 24.4�2.5 cm, P <0.05) and a greater AF vulnerability (mean AF duration, 1588�329 versus 25�34 seconds, P <0.05). Oral GAP-134 had no effect on AF vulnerability in UNPACED dogs. Compared with PACED-CTRL dogs, PACED-GAP-134 dogs had a longer estimated LA wavelength (10.2�2.8 versus 8.0�1.4 cm, respectively, P <0.05). Oral GAP-134 did not significantly reduce AF inducibility or maintenance in the entire group of 24 PACED dogs; in a subgroup of dogs (n=11) with less than 100% increase in LA systolic area, oral GAP-134 reduced AF induction from 100% to 40% and mean AF duration from 1737�120 to 615�280 seconds ( P <0.05). Conclusions— Oral GAP-134 reduces pacing-induced decrease in LA wavelength and appears to attenuate AF vulnerability in dogs with less atrial mechanical remodeling. Gap junction modulation may affect AF in some circumstances.